Giancarlo Fisichella looks likely to be in pole position for the first Grand Prix of the season in Australia.
The Italian driver took advantage of the best of the weather conditions to finish more than two seconds ahead of second-placed Jarno Trulli.
Heavy rain fell on Melbourne just after Fisichella's lap, making it very difficult for the other drivers.
World champion Michael Schumacher was the last driver on track and could only drive his Ferrari to 18th place.
Giancarlo Fisichella was quickest in Melbourne
He'll have the chance to make up some places on Sunday in the second qualifying session, but it will be very difficult.
New qualifying rules for 2005 see the times from the Saturday session added to a second session on Sunday to determine the final grid positions.
David Coulthard was the quickest British driver for his new Red Bull Racing team in sixth with Jenson Button two places behind in eighth.